Production of shaped objects from viscose



PRODUCTION OF SHAPED OBJECTS FROM VISCOSE Kurt Heuer, Oberbrnch-Grebben, Hugo Elling, Grebben,

and Richard Elssner, Randerath, Bez. Aachen, (fermany, assignors to American Enka Corporation, Enka, N.C., a corporation of Delaware N Drawing. Filed Oct. 17, 1955, Set. N0. 541,096 Claims priority, application Germany Nov. 25, 1954 2 Claims. (Cl. 18--54) This invention relates to a process for the production from viscose of artificial threads and other shaped objects, including films, having greatly improved properties as regards their resilience and their smaller degree of swelling. The invention also relates to the resulting products.

One of the principal objects of the present invention is to provide a new and improved method for spinning artificial products such as threads and other shaped objects from viscose in such manner as to confer upon them greatly improved properties as regards their strength and elasticity. A further object of the invention is to provide a new and improved method for producing prodnets of the kind just indicated having unusually strong and well-defined peripheral zones.- A still further object of the invention is to provide improved products of the kind indicated.

The manner in which these and other objects and features of the invention are attained will appear more fully from the following description thereof, in which reference is made to typical and preferred procedures in order to indicate more fully the nature of the invention, but without intending to limit the invention thereby.

A large number of different processes have been previously proposed for the production of threads and the like with particularly good strength and elasticity values. The best results are generally obtained with threads which have a strongly developed peripheral zone. In order to produce such threads it has been considered heretofore to be essential to operate with a spinning bath having a high zinc sulphate content.

Subsequently, processes were proposed in which small amounts of monoamines were added to the viscose or in certain cases even to the spinning bath, the said monoamines being soluble in the viscose and also in the spinning baths containing about 3-25% of zinc sulphate. The monoarnines are employed in an amount not more than about 4 millimoles per 100 grams of viscose. The use of these processes on an industrial scale, however, presents considerable difliculties, since it is necessary to adhere exactly to predetermined amounts of these monoamines and to the other prescribed spinning conditions in order that the desired technical effect may be obtained. -In addition, when using these processes, it is necessary to maintain withdrawal speeds of not more than 20-25 m./min., if the desired technical effect is to be obtained at all. Consequently, the use of monoamines on a large technical scale is not convenient and presents considerable operating problems.

According to the present invention, it has now been discovered that threads and other shaped objects having a strong peripheral zone and greatly improved strength and elasticity properties may be produced from viscose ifimidazole is added to a viscose and preferably a viscose which is not too ripe prior to the spinning or other shaping operation. It has been established that the difficulties arising when viscose containing monoamine is spun are obviated when using imidazole as additive in the manner indicated 7 and that it is possible to operate successfully with withdrawal speeds of 40-50 m./min.

The imidazole is added to the viscose in amounts of' 0.06-0.4 by weight, preferably 0.l2-.0.l5 by weight,

and may in fact already be added simultaneously with the dissolving of the xanthate.

The imidazole may be employed .with viscoses having a conventional composition, examples of which are those having 7'8% of cellulose and 5-7% of NaOH. The

spinning ripeness of the viscose preferably should not have a gamma value lower than 42; i.e., spinning preferably is done with an unripe viscose.

The spinning baths employed preferably contain zinc in the form of zinc sulphate in amounts of 30-50 g./l.; the acid. content (sulphuric acid) may fluctuate within the limits of 40-65 g./l.; while the sodium sulphate content may be within the usual limits, namely, between about 160 and 260 g./l.

The spinning bath temperature lies preferably between 45 and 70 C., and the withdrawal speed of the thread or other shaped object preferably is between 40 and 50 m./min. This speed may be further increased if known measures are taken to impart to the spinning b-ath,,at least on the first part of its travel after the spinning nozzle, a speed which is substantially equal to the thread speed, so that the friction between the thread and the spinning bath is thereby substantially reduced.

The bath zone is preferably at least 30 cm. long. The thread or other shaped object is then drawn or stretched by a factor of -120%, preferably -l00%, in a second hot bath (e.g., at a temperature higher than 90 C.) which contains 2-10 g./l. of H 80 The thread may thereafter be deposited onto a bobbin, into a centrifuge or onto a perforated web,

Threads spun by the process according to the present invention have strength values of 400-420 g./ den., and these values may be increased still further such as to 430-460 g./100 den. by subsequent stretching. They are characterized by a very high shrinkage, a high abrasion resistance value and a low degree of swelling.

In order to indicate still more fully the nature of the present invention, the following example of typical procedure is set forth, it being understood that this description is presented by way of illustration only, and not as limiting the scope of the invention.

Example Alkali cellulose consisting of linters and wood cellulose is sulphidized for 5 hours with 42% carbon disulphide and the Xanthate obtained is dissolved to form a viscose with 7.3% of cellulose and 5.5% of NaOH. During the dissolving operation, 0.12% by weight of imidazole is introduced into the viscose. The viscose is then filtered, deaerated and ripened in the usual manner,

and then spun with a viscosity of 60 poises at the gamma number of 44.0. The spinning bath has the composition of 52 g./l. of sulphuric acid, 40 g./l. of zinc sulphate and g./l. of sodium sulphate and a temperature of 7 58 C. The thread has 1000 individual threads withan individual titre of 1.65 den. and is guided over a path of 65 cm. in the spinning bath and is withdrawn over a suitable roller or godet at a speed of 21 m./min. The thread then travels through a second bath containing 2,914,004 Patented Mar. 7,

of about 120 tu'rns per meter. The thread is then washed, finished and dried after a final stretching of 8%. It has the following textile properties:

Strength, gJdeu. Elongation, percent dry wet dry wet While a specific example of a preferred method and product embodying the present invention has been described above, it will be apparent that many changes and modifications may be made in the methods of procedure and the products without departing from the spirit of the invention. It will therefore be understood that the example cited and the methods and procedures set forth above are intended to be illustrative only and are not intended to limit the invention.

What is claimed is:

1. Viscose spinning solution containing imidazole in the amount of 0.06-0.4% by weight based on the viscose.

2. A process for the production of regenerated cellulose threads from viscose, comprising incorporating into viscose 0.06-0.4% by weight based on the viscose of imidazole, extruding the resulting viscose into an aqueous bath having the composition of -50 g./I. of zinc sulphate and -65 g./l. of sulphuric acid, treating the resulting extruded object in a second hot bath containing 2-10 g./l. of sulphuric acid, and stretching same by a factor of 120%.

References Cited in. the file of this patent UNITED STATES PATENTS 2,077,412 Herzog Apr. 20, 1937 2,284,028 Ubbelohde May 26, 1942 2,506,249 Tammen May 2, 1950 2,516,316 Hare a..--- July 25, 1950 2,535,044 Cox Dec. 26, 1950 2,593,466 MacLaurin Apr. 22, 1952 2,648,611 Richter Aug. 11, 1953 2,705,184 =Drisch Mar. 29, 1955 2,732,279 Tachikawa J an. 24, 1956 2,772,444 Burrows Dec. 4, 1956 2,796,319 Studer June 18, 1957 2,810,658 Pontius Oct. 22, 1957 2,845,327 Lytton et al. July 29, 1958 2,853,360 Thumm Sept. 23, 1958 2,884,332 Locher Apr. 8, 1959 2,892,729 Howsmon June 30, 1959 2,904,446 Schlatter Sept. 15, 1959 

2. A PROCESS FOR THE PRODUCTION OF REGENERATED CELLULOSE THREADS FROM VISCOSE, COMPRISING INCORPORATING INTO VISCOSE 0.06-0.4% BY WEIGHT BASED ON THE VISCOSE OF IMIDAZOLE, EXTRUDING THE RESULTING VISCOSE INTO AN AQUEOUS BATH HAVING THE COMPOSITION OF 30-50 G./1. OF ZINC SULPHATE AND 40-65 G./1. OF SULPHURIC ACID, TREATING THE RESULTING EXTRUDED OBJECT IN A SECOND HOT BATH CONTAINING 2-10 G./1. OF SULPHURIC ACID, AND STRETCHING SAME BY A FACTOR OF 80-120%. 